chap 14 rate of reactions

• collision theory states that in order for a reaction to occur, reactant particles must collide with each other with energy that is equal to or higher than activation energy
• more concentrated solution has more particles per unit time which leads to more collisions. frequency of effective collisions increases hence rate of reactions increase.
• when gases are at high pressures, reacting particles are closer together, collisions between particles are more frequent, this increases the frequency of effective collisions, hence there is a higher rate of reaction
• a decrease in particle size increases surface area, hence reactant particles are more likely to collide due to greater surface area, effective collisions are more frequent hence there is a higher rate of reaction.
• increasing temperature causes an increase in kinetic energy of particles, so they can overcome the strong intermolecular forces of attraction and have more energy than the activation energy when they collide. This means that more collisions will be effective. Hence, increasing temperature increases the rate of reaction.
• if a reaction gives off a gas, we can find the rate of reaction by measuring the volume of gas given off at regular time intervals using a gas syringe.
• measuring of the rate of reaction through change in mass: gradient or slope of graph is an indication of the rate of reaction. initially, gradient of graph is steep hence rate of reaction is high. eventually, reaction stops as there is no more decrease in mass and graph becomes horizontal